1. Field of the Invention
The present invention relates to a photographing apparatus, such as a video camera, and a control method therefor.
2. Description of the Related Art
Recently, in a video camera, operations, such as exposure determination, focusing, and shake correction, which are important for photographing, have been all automated, and hence even a photographer inexperienced in operating a camera seldom fails in photographing.
There has also been proposed a video camera designed such that natural images can be obtained even when photographing is carried out while moving the camera intentionally during photographing, for example, performing a panning operation (an operation of horizontally moving the shooting direction of the camera) and/or a tilting operation (an operation of vertically moving the shooting direction of the camera) (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. H11-275431).
However, the operation for carrying out panning during photographing is not fully automated, and a large part of the operation depends on a photographer's skill. When panning is manually performed, the velocity of panning cannot be held constant, and degradation of image quality can occur due to a camera shake, which makes it difficult for a beginner to perform stable and high-quality video recording.
As a technique of correcting a camera shake occurring during a manual panning operation, there has been proposed a shake correction device e.g. in Japanese Laid-Open Patent Publication (Kokai) No. H05-014801, in which a correction mirror that tilts at an angular velocity proportional to the angular velocity of a video camera is incorporated in the video camera, and the optical axis of object light having entered a taking lens is finely adjusted using the correction mirror.
However, according to this technique, the panning operation of the video camera is manually performed by the photographer, and to enhance the stability of the panning operation, the shake correction is performed during the manual panning operation by finely adjusting the optical axis of object light having entered the taking lens, horizontally and vertically, in proportion to the angular velocity of the video camera. This technique, which is used solely for fine adjustment, is not at all configured to bend the optical axis at a large angle of several tens of degrees. Therefore, the technique is not suitable for a panning operation performed over a large angle so as to follow the motion of an object.
Further, as a technique of assisting the manual panning operation, a method is known, for example, in which when the photographer is performing a panning operation, a taking lens barrel is drivingly controlled so as to perform shake correction based on an output from an angular velocity sensor that detects a panning angular velocity, as well.
In this method, the panning operation of the video camera is performed by the photographer, and to enhance the stability of the panning operation, the taking lens barrel is slightly driven for the panning correction. However, since the amount of drive correction of the taking lens barrel is mechanically limited, it is difficult for this method to fully cope with panning operations which are performed at various velocities and in various amounts of panning. Further, this method requires getting experienced in operation of the video camera, and hence it cannot sufficiently serve as a method for a system that can be immediately used by a beginner.
To achieve stable video recording irrespective of the velocity and amount of panning, it can be envisaged as a suitable method to automatically pivotally move a taking lens barrel itself in accordance with a panning direction. However, a photographing apparatus employing this method has not yet been realized. Broadly speaking, as the photographing apparatus employing this method, there has been proposed an apparatus for use as a surveillance camera or the like, in which panning and tilting are performed with a camera body provided with a taking lens barrel placed on a rotary pan head or a table (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. 2002-369046).
However, the apparatus that performs panning and tilting with its camera body placed on the rotary pan head or the table is originally designed on the assumption that it will be installed on a table or a wall, and hence has no portability enabling the user to carry the apparatus. In addition, a large hemispherical space is required around the camera body so as to allow horizontal and vertical rotation of the camera body, which makes it difficult to achieve an excellent operability and a compact construction.
Further, if the apparatus that performs panning and tilting with its camera body placed on the rotary pan head or the table is applied to a consumer video camera, the following problem will arise.
FIGS. 25A to 25C are views showing, by way of example, the construction of a conventional consumer video camera provided with a rotary pan head as a panning mechanism, in which FIG. 25A is a front view, FIG. 25B a side view, and FIG. 25C a top plan view.
A video camera body 511 is provided with a taking lens barrel 512 and a viewfinder 513. Solid lines 512d in FIG. 25B indicate a boundary between the video camera body 511 and the taking lens barrel 512. The taking lens barrel 512 can be pivotally moved about a shaft 512a (512g) by an actuator 512e (512f) in a direction 512b (512h) for panning (tilting) photographing.
Two-dot chain lines 512i in FIG. 25C indicate a state where the taking lens barrel 512 is panned 60 degrees. As is apparent from FIG. 25C, during panning, the taking lens barrel 512 largely projects from the video camera body 511 to form an odd shape. This not only makes it hard for the user to hold the video camera in a hand for photographing, but also largely shifts the center of gravity of the taking lens barrel 512, which makes the shooting operation unstable. Further, there is a fear that dust or dirt enters the video camera body 511 and the taking lens barrel 512 through the vicinity of the boundary 512d. 
For the above described reason, if the conventional shape of the taking lens barrel remains unchanged, it is difficult to realize a video camera easy to operate in performing panning and tilting as desired.